The present invention relates to a method for preparing cells for cancer treatment and a kit for cancer treatment comprising cells prepared by the method. The preparation method of the present invention can provide F cells, which, in spite of having no difference in the proliferative capacity compared with mesenchymal stem cells expressing cytosine deaminase, which are harvested and used immediately after the culture, exhibit a very excellent tumor suppressive effect through the treatment together with 5-FC and induce a remarkable synergistic effect exceeding an effect from combinative treatment with an existing anticancer drug in cases of a combinative treatment with another anticancer drug. Therefore, the present invention can be utilized for a kit for cancer treatment comprising such F cells, and thus can be favorably used to maximize the effect of existing cancer treatments.